JPS6274648A - Plastic laminate having excellent gas barrier property - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field 1 The present invention relates to a plastic laminate, and more specifically to a plastic laminate with excellent gas barrier properties used for packaging materials, etc. .

[Conventional technology 1] Plastic films used as packaging materials for foods, drugs, chemicals, etc. are made of materials with low permeability to gases such as water vapor and oxygen to prevent deterioration of the packaged contents. There is.

In the case of packaging materials that require even higher gas barrier properties, materials in which aluminum foil is bonded to a plastic film, or materials in which aluminum is vapor-deposited on the surface of a plastic film have been used.

However, although packaging materials using such metal foils have excellent gas barrier properties against water vapor and oxygen, they have the disadvantage that they are opaque and the contents cannot be seen from the outside. In some ways, it was not appropriate.

On the other hand, films containing polyvinylidene chloride and vinylidene chloride as the main component and copolymers of this with vinyl chloride, methyl acrylate, methyl methacrylate, acrylonitrile, etc., and films containing polyvinylidene chloride and vinylidene chloride as the main component Vinylidene coated films, which are films made of polypropylene, polyester, polyamide, etc., coated with vinylidene chloride resin such as copolymers, are also used as gas barrier packaging materials.

These vinylidene chloride films themselves have barrier properties against water vapor and oxygen, but these gas barrier properties are not sufficient and are unsuitable for packaging materials that require a high degree of gas barrier property. Ta.

Furthermore, polyvinyl alcohol film, ethylene-
Polyvinyl alcohol films such as vinyl alcohol copolymer films are widely used as packaging materials because of their excellent oxygen and barrier properties. However, this polyvinyl alcohol film has the disadvantage that it has poor water vapor barrier properties, and furthermore, its oxygen barrier properties are degraded under conditions of high humidity. Therefore, when using polyvinyl alcohol film as a packaging material,
A laminated film in which a film having water vapor barrier properties such as a polypropylene film, a polyethylene film, or a polyester film is laminated on a polyvinyl alcohol film is usually used. However, such laminated films have not been able to fully demonstrate their functions as packaging materials that require high gas barrier properties.

In addition, although such a laminated film has improved oxygen and barrier properties to some extent under high humidity conditions, it has not been sufficient.

Therefore, in order to impart high gas barrier properties to such a laminated film, the thickness of the laminated film must be increased, and increasing the thickness of the film may reduce the transparency and flexibility of the laminated film. I hope it's damaged,
It has the disadvantage that it loses its suitability as a packaging material.

Several attempts have already been made to overcome deficiencies such as those described in (1) and (1). For example, U.S. Patent No. 4.10
As seen in the specification of No. 5,818, it is known that a plastic film having a multilayer structure has better oxygen and carbon dioxide barrier properties than an identical film having a single layer structure of the same thickness. There is. However, the laminated film described here relates to a multilayer film made of the same material, and its gas barrier properties have only been improved in terms of gas barrier properties against oxygen and carbon dioxide.

[Problem to be Solved by the Invention 1] In view of the current situation, the present inventors have conducted intensive studies with the aim of obtaining a plastic film that is transparent, has excellent gas barrier properties, and is suitable as a packaging material. As a result, the present invention was completed.

``Means for Solving the Problems 1'' However, key points to 9 of the present invention are that in a laminate consisting of a plastic film with excellent water vapor barrier properties and a polyvinyl alcohol film, a plastic film with excellent water vapor barrier properties is used. film and polyvinyl alcohol film YoQ f 2 to 4 MM film l
The present invention relates to a plastic laminate having excellent gas barrier properties, characterized in that at least two units of this laminate film are laminated, and mutually adjacent layers of the laminate are made of different types of films.

The present invention will be explained in detail below.

The plastic laminate of the present invention is made of a plastic film with excellent water vapor barrier properties and a polyvinyl alcohol film.

In the present invention, the plastic film with excellent water vapor barrier properties is based on ASTM F372 (temperature 40
℃, relative humidity 90% (hereinafter simply expressed as 40°C x 90%RH) water vapor il! : Passage rate is 50) 1 layer m
2・24t+rs, 20u thickness or less, more preferably 3
0 g/+62・24 I+rr, Thickness of 20μ or less is preferable. Such films include olefinic films such as polyethylene and ethylene copolymer films, polypropylene and propylene copolymer films, polyvinyl chloride and its copolymers, and vinylidene chloride/vinyl chloride copolymers. 7 types of polyvinylidene chloride films such as films, polyester films such as polyethylene terephthalate films, polytetrafluoroethylene films, etc.
Examples include vinylidene coated films in which polypropylene, polyamide, polyethylene terephthalate films, etc. are coated with vinylidene chloride RN4 resin.

In the present invention, polyvinyl alcohol film is
Polyvinyl alcohol preferably 70 mol% or more 1-. Refers to a film manufactured from the resin contained in the resin. Examples of such resins include polyvinyl alcohol resins obtained by saponifying polyvinyl acetate and ethylene-vinyl alcohol copolymers obtained by saponifying ethylene-vinyl acetate copolymers.

These films may be produced from raw resin by any known method such as solution casting, extrusion, and inflation.

In the laminate according to the present invention, it is effective to use a polyvinyl alcohol film stretched in the -axial direction or in the biaxial direction, since the gas barrier properties can be further improved. In this case, a method of manufacturing a laminate using a polyvinyl alcohol film that has been stretched in advance in a uniaxial direction or a biaxial direction, and a method of manufacturing a laminate using a polyvinyl alcohol film that has not been stretched, and then
A method of stretching this laminate in a uniaxial or biaxial direction,
Either method may be used.

As the stretching method, any known method such as a tenter method, a tube method, or a roll method may be used.

In both of the above two methods, the stretching ratio is vertical,
It is preferable that both sides be 1.5 times or more 1-.

In the present invention, a plastic laminate is defined as a two-layer laminate film consisting of a plastic film with excellent water vapor barrier properties and a polyvinyl alcohol film. I-, more preferably 12 below S lit, even more preferably l
O Qt rank or more! It refers to something that has been made llIK4.

At this time, the adjacent layers of the laminate must be made of different types of films, and a plastic film with excellent water vapor barrier properties and a polyvinyl alcohol film are laminated to form a structure in which they are laminated one on another. let

By structuring the laminate as described above, the water vapor permeability under the 40'C x 9o%R1+ row 1'1 of the laminate can be reduced to 1 g/ +n' ・2 4 f
irs, below, temperature 30°C, relative humidity 80% (
Below, in 111, acid 7 under the conditions of 30°C x 80% RI (indicated) Transmittance 0, 1 cc/1
62.2 4 hrs, al. +o or less, and transparency can also be maintained.

The laminate according to the present invention has the following advantages: - When the surface is made of a plastic film with excellent water vapor barrier properties, the other surface is a polyvinyl alcohol film. A laminate made of high-quality plastic films is preferred because it can be used for orgasm without distinction between the front and back sides. Depending on the application, it is best to use either a laminate where the surface is a plastic film with excellent water vapor barrier properties and the ground surface is a polyvinyl alcohol film, or a laminate where both surfaces are made of plastic film with excellent water vapor barrier properties. .

The thickness of the laminate according to the present invention can be selected from the range of 5 to 5 (I I) μ depending on the application and 1ζ from the viewpoint of smoothness, strength, flexibility, and cost. More preferably 10 to 200μ, even more preferably 12·λJ
A thickness of 100μ is preferable.

The thickness of the plastic film and polyvinyl alcohol film having excellent water vapor barrier properties may be appropriately selected so that the thickness of the laminate falls within the above range.

As a method for manufacturing the laminate according to the present invention, it can be manufactured by a known method such as a dry lamination method or a coextrusion method.

“Effect 1 of the invention: The plush laminate according to the present invention has excellent transparency,
It also has extremely high gas barrier properties, is flexible, and has excellent strength and V-economy.6 Therefore, it is used as a highly It can be used in a wide range of applications as a packaging material that requires excellent properties, and its industrial value is extremely high.

“Example 1 The present invention will be explained in detail based on examples below.
The present invention is not limited to the following examples unless it exceeds the gist thereof.

In addition, in the following Examples and Comparative Examples, the water vapor transmission rate is 40°C x 90% R based on ASTM F372.
Under the conditions of H, the oxygen permeability was measured at 30°C x 80%
Measurements were taken under H conditions.

Examples include axially stretched polypropylene films (water vapor permeability 8, 3
g/ +n2・24hrs, 20μ thickness, thickness 15μ)
Topolyvinyl alcohol film (vinyl alcohol 9
A laminated film 511 (containing 9 mol % and having a thickness of 14 μm) was formed by dry laminating using a urethane adhesive.
A laminate of approximately 100 mL was obtained (see Figure 1).

The water vapor permeability and oxygen permeability of this laminate were measured. The results are shown in the table below.

Example 2 Biaxially oriented polypropylene film (same sheet as in Example 1), biaxially oriented polyvinyl alcohol film (containing 99 mol% vinyl alcohol, Tr, Fli 4μ, stretching ratio 2×2)
) and the laminated film 5 using the same method as in Example 1.
A unit laminate was obtained.

The results of measuring the water vapor permeability and oxygen permeability of this laminate are shown in the table.

Example 3 A laminate of about 101'It was obtained by coextruding polypropylene, an ethylene-vinyl alcohol copolymer (containing 70 mol% vinyl alcohol), and a polyolefin adhesive resin as a bonding agent (fjS2). (see figure). The thickness of the laminate was 1()0μ. The results of measuring the water vapor permeability and oxygen permeability of this laminate are shown in the table.

Example 4 A film obtained by coextrusion in the same manner as in the example described in Example 3 (thickness is thicker than that of Example 3) was stretched in the direction of the two wheels (stretching ratio 2 x 2 >) and laminated. film 10
．． An 811-layer product ranked 111th was obtained. J7 size of laminate is 10
It was 0μ. The measurement results of water vapor permeability and oxygen permeability of this laminate are shown in the table.

Example 5 Using the same mu as used in Example 3, a laminate of layer 2 O111 was obtained. Its thickness was 100μ. The results of measuring the water vapor permeability and oxygen permeability of this laminate are shown in the table.

Example 6 A film obtained by coextrusion in the same manner as in the example described in Example 5 (thickness is thicker than that of Example 5) was stretched in biaxial directions (stretching ratio 2 x 2), Laminated film 20
A unit product M structure was obtained. Its 1rl thickness was 100μ. The measurement results of water vapor permeability and oxygen permeability are shown in the table.

As a comparative example, an axially stretched polypropylene film (water vapor transmission rate of 8.3 g
/I62・24hrs, 20μ thick, 15μ thick) and an ethylene-vinyl alcohol copolymer film (containing 40 mol% vinyl alcohol, n 314μ) were dry laminated using a urethane adhesive to form a laminated film 5Jli. A laminate of about 100% was obtained. The results of measuring the water vapor permeability and oxygen permeability of this laminate are shown in the table.

Comparative Example 2 Biaxially stretched poly7mid film (water vapor transmission rate 200H/
m2・24hrs, 20μ thick, 15μ thick) and a polyvinyl alcohol film (containing 99 mol% vinyl alcohol, thickness 14μ) were dry laminated using a urethane adhesive to form a laminate of 5 units of laminated film. Obtained. The results of measuring the water vapor permeability and oxygen permeability of this laminate are shown in the table.

Comparative Example 3 Polyvinyl alcohol film (vinyl alcohol 99
Biaxially oriented polypropylene film (water vapor transmission rate 8, 3 g/tI12・24 b
r! ! , 20μ thick, 23μ thick) were layered with Mt by dry lamination using urethane adhesive, and 3
A laminate consisting of layers was obtained. The results of measuring the water vapor permeability and oxygen permeability of this laminate are shown in the table.
Fig. 1 is a partial longitudinal sectional view showing an example of the laminate according to the present invention, and Fig. 2 is a partially enlarged longitudinal sectional view showing another example.

Claims (6)

[Claims] (1) In a laminate consisting of a plastic film with excellent water vapor barrier properties and a polyvinyl alcohol film, the two-layer laminate film consisting of a plastic film with excellent water vapor barrier properties and a polyvinyl alcohol film is used as one unit. 1. A plastic laminate with excellent gas barrier properties, characterized in that at least two units of films are laminated, and mutually adjacent layers of the laminate are made of different types of films. (2) Plastic films with excellent water vapor barrier properties must be selected from those with a water vapor permeability of 50 g/m^2, 24 hrs, 20 μ or less under conditions of a temperature of 40°C and a relative humidity of 90%. A plastic laminate with excellent gas barrier properties according to claim (1). (3) The plastic with excellent gas barrier properties according to claim (1), wherein the polyvinyl alcohol film is selected from polyvinyl alcohol resins containing 50 mol% or more of vinyl alcohol. laminate. (4) Temperature of plastic laminate: 40℃, relative humidity: 90℃
Water vapor transmission rate under the condition of 1g/m^2・24
hrs or less, and the oxygen permeability under the conditions of temperature 30℃ and relative humidity 80% is 0.1cc/m^2・24
hrs. A plastic laminate with excellent gas barrier properties according to claim (1), characterized in that the gas barrier properties are below ATM. (5) The plastic laminate with excellent gas barrier properties according to claim (1), characterized in that it is selected from polyvinyl alcohol films that are uniaxially or biaxially stretched. (6) A plastic film with excellent water vapor barrier properties is further laminated on the surface of the plastic laminate on the polyvinyl alcohol film side.
A plastic laminate with excellent gas barrier properties according to claim (1).